.box {
    display: flex;
    height: 800px;
    flex-flow: row  wrap;
   }
   
   .item {
       width: 200px;
       height: 200px;
       margin: 15px 15px;
       background-color: rgb(128, 78, 78);
   
       text-align: center;
       line-height: 200px;
       color: red;
       font-size: 50px;
   }